This application is cross-referenced to the commonly assigned application of Vincent D. McGinniss, U.S. Ser. No. 519,409 entitled "Cathodic Electrocoating Composition and Process", filed on Oct. 31, 1974, the disclosure of which is expressly incorporated herein by reference.
This invention relates to electrodeposition of water-dispersed, heat-curable polymers onto a cathode substrate and more particularly to cross-linking amine groups on said electrodeposited polymers with a heat-reactive alpha-beta-ethylenically unsaturated carbonyl.
Several processes for electrodeposition of heat-curable electrocoating polymers onto a cathode substrate disposed in an aqueous electrocoating bath have been suggested. For example, U.S. Pat. No. 3,617,458 discloses an electrocoating epoxy polymer having pendant amine groups which are neutralized with an inorganic acid to render the polymer water soluble. The epoxy polymer also contains pendant carboxyl groups which cross-link with the epoxide (oxirane) groups of an epoxy resin upon heating to form a cured coating on the cathode substrate.
It now has been found that an alpha-beta-ethylenically unsaturated carbonyl cross-linking agent having at least two alpha-beta-ethylenically unsaturated groups cures a polymer which has been electrodeposited onto a cathode substrate. The electrocoating polymer contains pendant primary or secondary amine groups which are used both for rendering the polymer water soluble and for cross-linking with the alpha-beta-ethylenically unsaturated carbonyls.